Strong Numbers in a Given Range in C++

April 1, 2022

Strong Number in a Given Range

Today in this page we will be discussing the code to find the Strong Numbers in a Given Range in C++  programming language.

Strong number is a special number whose sum of the factorial of digits is equal to the original number.

For Example: 145 is strong number. Since, 1! + 4! + 5! = 145.

Strong Numbers in a Given Range

The idea is to iterate from (1, N)  and check if any number between the range is a strong number or not. If yes then print the corresponding number, else we need to check for the next number.
Let’s understand this with help of some examples

Input: N = 100 
Output: 1 2 
Explanation: 
Only 1 and 2 are the strong numbers from 1 to 100 because 
1! = 1, and 
2! = 2

Input: N = 1000 
Output: 1 2 145 
Explanation: 
Only 1, 2 and 145 are the strong numbers from 1 to 1000 because 
1! = 1, 
2! = 2, and 
(1! + 4! + 5!) = 145 

While loop in C

Strong Numbers in a Given Range C++ Code

Run 
#include <iostream>
using namespace std;
int main()
{
    int i, n, n1, s1 = 0, j, k, en, sn;
    long fact;
    
    sn = 1;
    en = 200;
    cout << "\n Find Strong Numbers within an range of numbers " << sn <<" and "<<en <<endl;
    cout << " The Strong numbers are: ";
    for (k = sn; k <= en; k++) 
    {
        n1 = k;
        s1 = 0;
        for (j = k; j > 0; j = j / 10) 
        {
            fact = 1;
            for (i = 1; i <= j % 10; i++) 
            {
                fact = fact * i;
            }
            s1 = s1 + fact;
        }
        if (s1 == n1)
            cout << n1 << "  ";
    }
    cout << endl;
}

Output

 Find Strong Numbers within an range of numbers 1 and 200
The Strong numbers are: 1 2 145
Software Engineering SDLC